The American Joint Committee for Cancer Staging and End Results Reporting is engaged in a clinical research project to develop staging classifications for cancer of all anatomical sites. The procedural method for establishing these stage classifications is by production of information-gathering protocols and their use in a retrospective study. The accumulated data is subjected to statistical analysis, and from the results of this analysis a classification of extent of disease under the TNM system is developed. The developed staging systems are published and are recommended for use in prospective studies to further confirm their validity.